I really do not advise using GAP unless you have absolutely no other option or are very curious.

It was originally for an older version of Gimp and now many of the functions do not work 100% (if at all) add to that a very steep learning curve, picky about layer names..etc..etc.

There are newer equivalents for parts of GAP. An example is the GAP morph plugin. That can be used on its own, but these days the G'mic interactive morph is an easier alternative.

Quick example:

I've used it before in the past, so I thought, I might as well give it a shot for gimp 2.10.22. I tested it to see if it works when creating gif animations from video clips and it does.

For that, I would just use ffmpeg. Many other easier tools available as well as on-line converters. I fail to see any real use for GAP, to be honest, but that's just me.