First off, the VUSO qualifier can't be a measure for starting players - it has cruel conditions which can only be mastered by masters of the game - Legends and above. I played a 71 today ;)
QuotaRelief: what do I need to do to get better and earn credits (not coins) that I can use to buy better equipment.
If you think to win those credits, be warned that it doesn't work this way. You rather have to get better equipment to - perhaps - have a chance to win something.
Despite of the misleading $ displays at certain places, this site is not really suitable to make a fortune. 99 % of these "$" are mere credit software licences "of no monetary value" (quoting the T&Cs).
The "Get Credits" section shows how to obtain them, either paying with money or paying with loads of your time. I've come to see my Euro spendings as investments in my leisure, and I received a lot for up to 10 € per month.
To become better, you need to practice and grind. If you want to win credits, the PC version is probably more suitable. There are buy-in RGs and Brackets, and there are Challenge games of Matchplay, Skins and Blitz (with a lot of sharks around).
Traditionally, we would recommend to play strokeplay on all courses to get to know them, but I can't make a recommendation for mobile play.
Better equipment comes with higher levels, and the ladder becomes really steep, requiring a lot of XPs to arrive at certain clubs.
So, it depends on the time and money that you are willing to sacrifice to the game. Most importantly, have fun!!