They do have a different playstyle than that of BB/CA/DD and not everyone learns those different ways of playing. Because of that some folks won't use them in Naval Battles because they are trying to play their best options for gaining Stars to help their clan.
I can't think of a dedicated submarine guide to point you to, but if you or your clanmates need information on how-to-CV you can use my old compendium:
Joined KSC in Season 9 and ended up on their Hurricane team as the CV player. Played Season 10 as the same and the team transferred to KSC toward the end of the season. I stayed with TNG until the season ended, then followed the team to KSC. Played 2 or 3 other seasons with KSC before leaving for [WG] after getting hired.
I played this current Clan Battle season with the second Div for KSC. We floated around Hurricane 20-110 for the last few weeks. Didn't play all the matches, but my record this season was: 123 W, 67 L
devtrackers.gg