Hey we tested out your map in the recent impromptu playtest but it appears you only have one respawn point in the map. You will need separate respawn points for each team, selecting in each the specific team choice from the dropdown list:
Here's a quick tutorial page on how to create your first spawn room:
https://developer.valvesoftware.com/wiki/TF2/Creating_a_Spawnroom
The basic premise is that there should be a dedicated room for each team to spawn in, a door to close it off from the rest of the map, and a 'respawn room visualizer' which blocks enemy players from entering into the spawn room (all described in the above link).
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Generally your map layout seems a little bit small, and a little bit random. For gameplay reasons you may want to simply copy the geometry you have at the moment, copy it, paste it, and rotate the pasted copy 180 degrees (ctrl + M for rotate dialogue):
The floor of the map being just skybox means players will just fall and get stuck down there, you may want to simply, for the sake of quickness, add a trigger brush and make it a hurt zone (so people who fall down there just die):
Your map will also require an objective! If you have ABS's
mapping resource pack installed you can
open the gametype library and copy/paste out the objective entities for your map to function.