Hi!
I’m not necessarily the best person to provide specific wiring advice but I wanted to make sure you were aware of the following page: Blue Series Dimmer Switch • Wiring Schematics | Inovelli Help Center
You mentioned that you were looking at wiring diagrams online but I’m not sure if these were the specific ones you found. There’s a Multi-Way (3-Way) + Auxiliary > 3-Way Non-Neutral Wire Installation section that is likely applicable/extensible for your situation.
You may also find this post helpful (particularly JohnRob’s diagram), it looks like someone else was dealing with a similar no-neutral 4-way wiring situation: 4-Way with no Neutral - #15 by dwright34