You need to create a compiled version of the script, specifying your username and password when exporting. Actually, this is what the premium version is for.
@505167790 The way I solve that kind of problem is with if statement.
First I load the proxy. Then Get on the link, then Status (these are functions in Http Client). So I go to Script Logic choose IF expression. If [[SAVED_STATUS]]!=200 (200 is code for successfully loading page) then load proxy Get on the link, then Status and so on...