I have the same problem

Ya same

this is normal and robes are not yet integrated in the mod and if you got the vanilla symbiotic husk you can't bite
This mod overrides the following vanilla content:

- Husk Infection originally found in "Content\Afflictions.xml"

Same problem here.

since no one actually answered OPs question, you need to create a new item called a Symbiotic Calyx Injector, and administer it to your character, then you get the bonuses like pressure immunity and waterbreathing, the creator of the mod added a link to a guide that has all this information, it's at the bottom of the mod description under "Useful Links"

new update kinda fix your problem
Fix non-modded husk symbiosis not working
Fixed crush depths warning
Being severely burned can kill a latched shambler head that's trying to hijack your body
Default husk infection now offers pressure resistance equal to a regular diving suit and greatly extends the amount of time you can survive without breathing, but doesn't remove the need to breathe entirely