Do you have to sell at the end, or can your end balance be in BTC?
You don't have to sell. Conveniently, the resulting amount of BTC will be displayed in USD.
Can you only access the price data within the testing time frame (7 days)?
It might not be enough data to bootstrap some indicators until they are reliable
At the start, each algorithm is pre-initialized with 100 bars of history trading data. This should be enough for most indicators. If not, please let us know.