College student dependents were to get a one time $500 credit, how do I receive?

There is no one time $500 credit for college students.  You have been misinformed.

If you are claiming a college student  over the age of 18 as a dependent you get the credit for other dependents for them.   You do not get the child tax credit for a child who was over 18 at the end of 2021.

CREDIT FOR OTHER DEPENDENTS

https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-credit

You may be inquiring about the 'Other Dependent Credit' for children over the age of 17. Details are listed below and you can use the links provided for additional information.

The $500 Credit for Other Dependents (aka “Family Tax Credit”) was signed into law as part of the 2017 Tax Cuts and Jobs Act and is in effect for tax years 2018 through 2025.

The credit allows taxpayers a credit for certain dependents that don't qualify for the Child Tax Credit, such as qualifying children age 17 or older, adult dependents, and dependents who have an ITIN.

To be eligible for this credit, the person(s) being claimed must fit the definition of a qualifying child or a qualifying relative, as defined here:

Qualifying child

• They are your biological child, stepchild, adopted child, eligible foster child, sibling or half-sibling, stepsibling, or an offspring of any of these
• They haven’t already been claimed for the Child Tax Credit or Credit for Other Dependents, either by you or by anyone else
• They are a U.S. citizen, U.S. resident alien, or U.S. national
• They aren’t filing a joint return with their spouse
• They are under the age of 19 (24 for full-time students; no age limit for permanently and totally disabled children)
• They live with you for more than half the year (exceptions apply)
• They didn't provide more than half of their own support for the year
• What is the Other Dependent Credit?

There is no  $500 credit for  College student dependents (not even one time).  There was covid relief payments for college students.  This money was administered  by the colleges and is NOT claimed on your tax return. It was not a fixed amount, e.g. $500.

The first $500 dependent stimulus was only for children under 17. The 2nd $600 was for all dependents (as is the 3rd $1400 stimulus).  If you did not get the 2nd ($600 each) stimulus for your student dependents, you should have claimed it on your 2020 tax return as the "Recovery rebate credit".  If you failed to do so, you can file an amended 2020 return to claim it.  Note: the $1400 3rd stimulus/rebate credit is claimed on the 2021 return.

Reference: https://ttlc.intuit.com/community/taxes/discussion/re-adding-kids-to-my-taxes-for-the-stimulus/01/1762866#M625579

As others have already indicated, the $500 Other dependent credit  is every year (not a one time credit) and is for all dependents, not just students.