What time signatures Tracker can handle?

The Polyend Tracker doesn't have a time signature setting as such, it's more flexible than that. Every pattern has an arbitrary number of steps and you can decide on your own how to interpret them. For example, by default, the length of a pattern is 32 steps. So two 4/4 bars when one quarter is 4 steps each.

But you can just as well set a pattern to have 96 steps which will yield eight 3/4 bars when one quarter is 4 steps each. And you can take that same pattern, increase tempo two-fold, and now have four 3/4 bars where each quarter is 8 steps each which is useful for rapid shots.

Similarly, you can write songs in 5/8, 7/8, or any combination of those. You organize your patterns.