Seeking Guidance on Correctly Using the CB-3000 Chastity Device

I’m keen on trying out chastity play. After a suggestion, I bought a CB-3000 from CB-X and followed their sizing chart. However, none of the included u-rings worked for me. So, I purchased two more in L and XL sizes. The XL ring fits (it’s 2 1/4 inches or 57.2 mm), but only at an angle. This makes the three pins pinch my scrotum, which stops me from locking the chastity cage.

I’d appreciate some guidance: Is it because my scrotum is tucked close to my body and doesn’t hang much? Or maybe it’s just too large? It could also be that I’m not placing the u-ring correctly.

Eager for your thoughts.