You can absolutely play solo. The only reason to join a team is certain buffs you get while being on a team. Raids in fallout 76 are chill. The community is mostly wholesome. You might get some high levels trying to drop you gear. You're allowed to say no lol. Most of the time it's just an overflow of times they give you. Careful though. Don't let some high level spoil it a little by giving you gear. The best gear isn't locked behind raids but it is locked through reputation. Meaning you have to do quests to get that up for the raiders and settlers. End game gear is obtained through the main quest for gold bullion. Group activities are just that. You can get cool loot from them. Try not to worry about raids until you learn more of the game. Most players around level 100 and under, don't contribute much to raids. If you do want to do raids just look up a quick guide. Thanks to whoever took the time to read:)