This sounds similar to a Melico unit or two that I have that I still use from time to time (at least until one of the tubes in them burns out). So you have confirmed that it is an integrated timer that is calibrated in logarithmic units. The timer likely is not a timer like you are used to seeing, but it will likely still work.
This unit is basically a balance bridge measurement unit; The dial Y, M, C, Timer and Aus off: (I suspect that AUS is the german equivalent of "off" or "standby") Each one is used to compare the reading being made at the time against a previously stored value.
For Y setting of the Y/M/C/Timer/AUS/OFF switch you place the probe under the image under test and then set the Y filtration in the enlarger filter pack or dichroic head to cause the needle measurement to null mid way between -1 and +1 to balance the bridge circuit. The balance point is set by the setting of the calibrated Y dial, calibrated Y1-Y5.
Similarly you adjust the Magenta and Cyan filter packs or dichroic settings so that the filtration nulls the setting against the reference filter setting dial value.
(With RA-4 filtration Cyan is almost always set to zero- with RA-4 you can ignore it).
When the selector switch Y/M/C/Timer is on timer there are no filter packs to adjust; here you balance the time bridge integrator against the light coming in (as may have been varied by the negative density, and the density of the filters, as well as the sensitivity of the paper, which is adjusted for by the paper sensitivity dial, by moving the setting of the Log D graduated timer dial unit the meter balances between -1 and +1. The paper sensitivity dial is usually only varied when you change paper lots, or types of paper.
The power of this type of timer set up is that it maintains a constant birghtness X time of exposure light integration function. Changes in filter factor, aperture, head height or negative density will also be compensated for to try give the same image density in the print where the probe is positioned.
Some setting on the Y/M/C/Timer/AUS/off dial will cause the power to the enlarger outlet to go off. When the switch is set to Y,M,C, or timer I suspect the power to the enlarger socket will be on. When you find the setting that turns the enlarger off, you are in the ready to expose stage; press the exposure button, and the integrator timer will run and turn the enlarger socket on for the amount of time that the bridge setting previously has set up to time.
Some photo sensors can get saturated under normal room illumination and take a few minutes to start to work once in the dark; I get in the habit of flipping the sensor upside down when I take it off of the easel after measurement so I don't have to wait after I turn off the lights and start the next round of using the analyser.
You can likely start to use this unit on B&Wb efore you get into colour to get a better feel for it. Just use the paper density and timer function; ignore the Y.M and C settings for now.
Print a b&w image with a convetional timer controlling the enlarger light. Dry the image if using FB paper.
Then place the analyser sensor over the light toned part of the image where there is just the first step from all white. Set a mid range of sensitivity of the paper sensitivity dial. Now set the timer dial unit the indicator balances.
Set the unit to expose, and time how long the timer leaves the socket for the enlarger on after you press the expose button. Compare it to the time that you actually used to make the print. Adjust the paper sensitivity and timer dials unit the exposre duration matches the conventional timer time; it is an iterative process.
Then you are calibrated to the paper used to make the print. Make note of the sensitivity setting; write it on the paper envelope etc.
Then you can change the aperture or the enlarger head height, or filtration. Place the sensor in the projected image where you want the first non white tone of grey to appear in the print and rebalance the timer dial; don't change the paper sensitivity. Re-establish the filtration, and make the new print; the same tome of light grey will be re-produced in the area where the sensor was positioned to meter the negative.
Sometimes the sensitivity and timer dials can be used to figure out the density range of the negative too. I am running out of room in this post, and will post separately on this idea.