What is ALC on a preamp?
If you look at the datasheet, there is an example application circuit:



Notice how the amplifier is used for amplifying for both recording and playback.  The same tape head is also used for both functions.

ALC (automatic level control) was an important function in tape recorders, as the signal had to be the right level, strong enough to overcome noise but not too high to cause saturation.  A variable-gain amplifier is a bit tricky to do without distortion, so having it integrated into the preamplifier was a convenience for the system designer.

I don't know what you plan to do with the part, but an obvious choice would be an audio compressor.  It won't be super high-fidelity, but maybe good enough for a guitar stomp box.