When building quotas, I've run into two issues:

1) Once the quota is added, editing the quota URL doesn't work. The field label says "Quota Message" (instead of "Quota URL") and changing the URL and pressing Save Quota does not update the URL.

2) Passthru variables do not work on Quota URLs, despite the documentation saying that it should (http://docs.limesurvey.org/URL+fields#Places_to_use_URL_fields). The URL ends up showing a bunch of HTML code suggesting that the variable is missing:

http://dkr1.ssisurveys.com/projects/end?rst=2&psid=%3Cspan%20style=%27background-color:%20#eee8aa;%27%3E%3Cspan%20title=%27Undefined%20variable%27%20style=%27border-style:%20solid;%20border-width:%202px;%20border-color:%20red;%27%3E%3Cspan%20title=%27Undefined%20variable%27%20style=%27color:%20red;%20font-weight:%20bold%27%3EPASSTHRU%3C/span%3E%3C/span%3E%20:%20%3Cspan%20title=%27Undefined%20variable%27%20style=%27border-style:%20solid;%20border-width:%202px;%20border-color:%20red;%27%3E%3Cspan%20title=%27Undefined%20variable%27%20style=%27color:%20red;%20font-weight:%20bold%27%3Epsid%3C/span%3E%3C/span%3E%3C/span%3E

Quota URL is: http://dkr1.ssisurveys.com/projects/end?rst=2&psid={PASSTHRU:psid}

The passthru variable does work in the End URL.