There is a bug when adding new Zotero group accounts in WP.
Steps to recreate:
1) Create Zotero API:
Go to Zotero, create a new API Group key: https://www.zotero.org/settings/keys/new
Untick all Private Library access options
Select appropriate Group access options
2) Create WP Zotpress Account:
Go to WP Zotpress > Accounts tab (/test/wp-admin/admin.php?page=Zotpress&accounts=true)
Select Account type "Group"
Add a user ID as instructed.
Add a Private Key as instructed
Add a nickname
3) Retrieve feed of Citations from Zotero into Zotpress:
Go to Zotpress > Citations tab
Error message. "Warning: DOMDocument::loadXML() [domdocument.loadxml]: Start tag expected, '<' not found in Entity, line: 1 in admin.default.php on line 257"
Use Zotero GROUP ID and not User ID as instructed by Zotpress.
Group ID is only available if you make the group private in Zotero and look at its url, instructions aren't provided in Zotpress.
Would be very helpful if this was made clear in the Zotpress Add Account page (e.g. if field description changed depending on the account type option chosen, plus instructions on where to get it in tooltips.)