Trustlines are necessary if you want to receive payments in a currency different from XRP. When receiving a deposit from a gateway you will need to have a trustline for that gateway so it can pay you.
For example, in order to receive payments denominated in BRL issued by rippex, you need to create a BRL trustline to our issuing BRL issuing address: rfNZPxoZ5Uaamdp339U9dCLWz2T73nZJZH
If you want to deposit bitcoins using the Rippex Bridge, you need to create a BTC trustline to our BTC issuing address: rKxKhXZCeSDsbkyB8DVgxpjy5AHubFkMFe
See how to create trustlines:
The limit amount should be high enough so you don't have to adjust it anymore, we suggest setting a very high amount, like 1 billion - for almost anything it is a high amount =). This is the maximum amount your account can hold.
You can always check a gateway's issuing address by adding /ripple,txt to its domain and looking at "[accounts]". See https://rippex.net/ripple.txt
#Rippex [accounts] #BRL rfNZPxoZ5Uaamdp339U9dCLWz2T73nZJZH #BTC rKxKhXZCeSDsbkyB8DVgxpjy5AHubFkMFe #Rippex HotWallets [hotwallets] #BRL rDb6qVhDdAybg9ARF2Yy64AAdk17Bi4M2q #BTC rf6eUJWaaV71XPzLBxiwiZ1gb9PR1CcW71 rpeKCr6Cc5mCj8GUUL4fPjeH5YXG3X1mYf [domain] rippex.net [currencies] BRL BTC