Using the key "Brian" on the image tells you to enter the link above using the code "HEMADEYOU". Using this and entering sends you to a 10 question quiz with II questions. getting 10/10 gives you the keyword "Line".

The hint in the completion screen references a line said by Pickle in "Crappy Anniversary" at 5:13. However, going to the Crappy Anniversary thumbnail, a hidden code can be seen when the colors are adjusted. This code translates to "COMICTWO" with the key "Line". (Credit to PigDoggo on Discord)

(Line is the second keyword needed for the final result at the end BTW)