The error means that you list items under inappropriate for GTC duration either listing type (auction) or category.
Please note, some of the eBay categories do not support GTC duration.
To solve the problem you should:
- change listing type (from auction to fixed price):
for M2E Pro based on the Magento v 1.x http://docs.m2epro.com/x/PQAJAQ
for M2E Pro based on the Magento v 2.x http://docs.m2epro.com/x/UwItAQ
- change eBay category
- change listing duration from GTC to any other.