Make sure that the email linked to your account is correctly input and you are able to access the account. In DevEx FAQ Support it states that you will only be sent an invite if they deem your request to be eligible to proceed.
I would recommend that you look through your Roblox transactions to tally up what actual robux are eligible to be exchanged. You can also contact support explaining you would like a further explanation about why your requests have been rejected repeatedly. Unfortunately, Roblox support is not always helpful and can return messages generated by auto response bots.
Yeah I know for sure it’s my email, and I already did tally it up. Furthermore, I only did 30k (the minimum) as a test but either way I have 600k+ earned.
To anyone else with this problem, I emailed Roblox support and it was a problem on their end. They accidentally had made a typo in my email, and I never received the registration link.