As mentioned in page 15 and 17 of https://techcommunity.softwareag.com/ecosystem/documentation/webmethods/wmsuites/wmsuite10-1/readme/MywebMServer_readme_10-1.pdf (see attached screenshot), MWS product design has been changed to stop using database as a JMS provider for MWS cluster, and instead switched to use Universal Messaging as JMS provider. The JMS provider is not only required by MWS cluster but also Central Users (CDS) which is applicable in your case. Please see detailed explanation and arrangements from R&D for the change below.
The decision to remove the database-based clustering was driven in an effort to improve robustness, as the database cluster implementation has caused significant issues in large MWS customers. It was assumed that MWS clustering would only be needed by BPMS customers and that they would have UM in their landscape anyway (or at least would have after a migration from Broker). There is an additional use-case of IS-only customers using Central Users (CDS). This setup also requires MWS clustering to be configured, even if there is only a single MWS, because each CDS client (i.e. each IS) is effectively a mini-MWS that needs its state synchronized using that mechanism.
MWs Product Managers have agreed that from a licensing perspective, They can grant a free limited-use UM license to any customer who does not have UM. For customers using Broker, they should have migration to UM on the roadmap due to the future Broker deprecation plan. Until then, they will help customers to get a free UM license limited for MWS usage only.