1. Coins can be earned through Head-to-Head Coin Room matches or TopGolf driving range unless you purchase them which I wouldn't recommend. They're only good for upgrading apparels & renting (that's right, RENTING not purchasing) Coin MK# club sets as far as I know so they're pretty much useless. Don't bother.
2. Other than what Don suggested, another possibility is probably the duration (the number of hits) you purchased is all used up. Join any country club above level 4 and they're available for free as long as you stay in the CC.
Welcome back and enjoy!