$ENV{MOZREPL_TIMEOUT}= 60;
[download]

is plain Perl code. Maybe it is time to acquaint yourself with special Perl variables as described in perlvar?

I also did try my suggestion before posting it, so the repetition of ->repl->repl-> is correct. If you doubt my advice, maybe you want to verify it yourself?

The timeout default setting is set by MozRepl. I suggest you consult its documentation or source code to find more details.

If you are unclear about a concept or term, like "ad blocker", maybe using a web resource like Wikipedia or Google helps - Ad filtering is the term Wikipedia suggests to me, and ad blocker will likely also return relevant search terms.