What external link? if it's beyond playstore or poloniex site then that's not a good idea to install that app into your phone it might be a scam or fake Poloniex app.

You can share the link here and let us check if it's legit or not.

Also, take note that Poloniex has had hack incidents before and I don't think it's a bright idea to stay trading on Poloniex so once you can able to withdraw your funds from them better switch to another exchange.