Hi Kai,
If a user doesn't have the Unrestricted cluster creation entitlement, then they can only create compute resources using their granted policies.
It will not let you create clusters even if you have credits.
Here is relevant documentation:
https://free.blessedness.top/en-us/azure/databricks/compute/configure#compute-policy
To have full access to Databricks, you will need to upgrade your subscription from the student plan to a Pay-As-You-Go plan.
Feel free to accept this as an answer.
Thankyou for reaching out to The Microsoft QNA Portal.