From the manual;
The AC output cable can be connected directly to the terminal block ‘AC-out’.
From left to right: “N” (neutral) , “L2” (phase 2), “PE” (earth) and “L1” (phase 1)
With its PowerAssist feature the Multi can add up to 3kVA (that is 3000 / 120 = 25A) to the output L1 during periods of peak power requirement. Together with a maximum input current of 50A this means that the output can supply up to 50 + 25 = 75 A. An earth leakage circuit breaker and a fuse or circuit breaker rated to support the expected load must be included in series with the output, and cable cross-section must be sized accordingly. Victron Energy recommends to use the Blue Sea systems GFCI circuit breakersPN. 309X or 310X. The maximum rating of the fuse or circuit breaker is 75A.
so it looks like a 75A GFCI main coming into the panel is needed. I can't seem to find the part numbers listed on Blue Sea's website nor do I see any GFCI breaker listed at 75A. I also am having a hard time finding an alternative source for a breaker with these specs can I get a link to something that would work?