The Player recognizes all the time signatures provided in the editor. However some styles will not play some time signatures (an error message will show when attempting to play the song). For example Pop-Shuffle does not play in 3/8; Blues-Lucille does not play in 5/8.

This is how they are interpreted:
4/4, 3/4 and 2/4 simply play as written in all styles

2/2 plays as 4/4;
3/2 plays as 3/4 + 3/4;
5/4 plays as 3/4 + 2/4;
6/4 plays as 3/4 + 3/4;
7/4 plays as 4/4 + 3/4;
There are no alternative (reverse) options currently.

3/8, 5/8 play as written (available with most styles);
6/8 plays as 2/4 so a triplet based style like Afro 12/8 is recommended for this time signature;
7/8 plays as 2/4 + 3/8 and does not work with triplet based styles like Swing or Afro 12/8;
9/8 plays as 3/4 so a triplet based style like Afro 12/8 is recommended for this time signature;
12/8 plays as 4/4 so a triplet based style like Afro 12/8 is recommended for this time signature. 12/8 is considered as 6/4 when generating even 8th (non-triplet) styles.

You can use more than one Time signature within a song, to create sophisticated compound time signatures.
Here’s an example of 9/4:

And the various  x/8 time signatures can work with each other for songs having 8th feels.
You can use compound signatures, here is how.

Note: 4/4 is the default time signature if none is chosen at the beginning of a song. Always make sure there is a Left barline (recommended, Left double barline) at the first space, first measure appearing after the time signature so the player interprets the beginning of the song correctly.