Reach out to AP_CustomerService@harvard.edu to talk through that option on a case-by-case basis. It is not recommended unless the transaction is over $50k, in which case a check would be required.
Most common troubleshooting: Check their browser and be sure to use Chrome or Mozilla, which are recommended by the B2P software provider, Jaggaer. If they are on an Apple computer, Safari security settings can cause issues.
Other troubleshooting:
Use a laptop or computer. Phones and tablet versions of browsers may cause other issues.