I will support that in almost everything you do in Colombia, you will need whatsapp. If you go the route of mototaxis (the following is my impressions, I did not use them), there is a large group of them at the bridge in central Minca, and if you need an early pickup one day with one of those, talking with them the previous day would work. If you want to have pickup by them at El Dorado, then you will need a whatsapp number for one of them ahead of time, they are not standing around at the lodge.
With regards to transfer to El Dorado using Silvana, I arranged that using whatsapp the day before.
Niels