Reaching successive levels is basically a measure of your experience or how much you play. This will give you access to more equipment in the pro shop to help your game but is not related directly to tier advancement.
Here is a good link that is often used by forum members and WGT staff to explain tier requirements.
Not sure what you mean by being stuck at hack +... you are obviously at the Master tier and should have access to equipment requirements beyond hack+ and up to level 64. Note that in pro shop some equipment (for example your putter) is available for lowest hack level but will require experience like level 62+, but this has no effect on your ability to level up or tier up. It just tells you why some equipment is available or locked.
You are on the right track by playing ranked stroke play games to advance tiers. You will just need to get your average down and play a minimum number of rounds in your tier as seen when you click the link.
Playing tourneys and multiplayer matches is not a requirement but can help to accelerate your level advancement and tier promotion.
-Keith