The three values you need
The numeric trading account number, the trading password, and the server name exactly as displayed in your client area. Copy and paste all three rather than typing them.
Configuring the terminal
Set the chart timezone expectation before analysing sessions, add your instruments to market watch, and save a template so a reinstall takes a minute rather than an evening.
Authorisation errors
An "invalid account" message almost always means the server is wrong or the account belongs to a different platform version. Confirm the account is an MT4 account and not an MT5 one.