Elecrum Dash is an excellent wallet to use with CrowdNode.
In order to deposit make sure you have some DASH on your registered address (the DASH address associated with your CrowdNode profile)* and then proceed as follows:
Once you select "Spend from" on your registered address a green bar will appear to remind you that you are now using "Coin control":
Finally, go to the Send menu, to make a deposit:
* If you don't have enough DASH on your registered address, simply start by transferring to yourself in Electrum DASH to collect as much DASH as you like (or have!) on the registered address. Then proceed as shown above.