Any transactions like sending and interactions on hive blockchain like following, posting, replying, following, muting someone requires Resource Credits. If you can invest some hive power into your account like about 15 HP then there shouldn't be any problem. Or wait for sometime to recharge it. For more information, you can read these posts:

@peak.answers/what-is-rc-resource-credits-how-to-get-more
@shortsegments/what-are-resource-credits