Lost washer on Canyon vcls seatpost

I have the dreaded creaking of this seatpost on my canyon grizl https://www.canyon.com/en-us/gravel-bikes/adventure/grizl/cf-slx/grizl-cf-slx-8-di2/3476.html?dwvar_3476_pv_rahmenfarbe=R083_P03&dwvar_3476_pv_rahmengroesse=L

I went to fix this following this video https://www.canyon.com/en-us/gravel-bikes/adventure/grizl/cf-slx/grizl-cf-slx-8-di2/3476.html?dwvar_3476_pv_rahmenfarbe=R083_P03&dwvar_3476_pv_rahmengroesse=L and lost the washer into the abyss. Its no where to be found. Can I keep going without the washer. Do you know what size it is to get a replacement washer?