Where can I find bus schedule between Voss and Aurland?

http://www.nettbuss.no/bestilling/velg-avgang
Nettbuss express:

Bergen (Bergen busstasjon) - Aurland (Flåm stasjon)
søndag 20. august 2017
Bergen busstasjon 17:15
Aurland Flåm stasjon 20:20
03:05

Voss (Voss stasjon) - Aurland (Flåm stasjon)
søndag 20. august 2017
Voss stasjon
Nettbuss express NX 450 Voss 17:20 Aurland Flåm stasjon 18:30 01:10

Trains Bergen to Voss:
Avreise Bergen - Voss Søndag, 20.08.2017
Bergen Lokal mot Myrdal stop at Voss: Avreise 12:56 Ankomstkl. 14:15

Bergen Lokal mot Voss: Avreise kl. 15:14 Ankomst kl. 16:31

Bergen Region mot Oslo S stop at Voss: Avreise kl. 15:59 Ankomst kl. 17:09

If you have booked accommodations in Aurland, try corresponding with your innkeeper as to help with bus/coach options and alternatives. I had mid-week mountain lodge accommodations that were served by bus during weekends. Solution was the innkeeper arranging car service from the train station to the lodge.

Here's the Nettbuss Express NX450 Schedule from 19 June 2017 in PDF file format:
http://www.nettbuss.no/system/script/getfile.aspx?NkM1QzcyMkQ5QzBCMTY0OUQ4N0QzN0YzOUFGNEM1OURGRkFEQUVBNA==

Søndag (Sunday) NX450 Bergen – Voss – Flåm – Sogndal only runs three times per day (Sunday), departing Voss at 10:35, 17:20 and 19:00 reaching Aurland at 11:55, 18:43 and 20:30 respectfully.

If your goal is Aurland by mid-afternoon, you could take the train from Bergen via Myrdal to Flam. See NSB Schedule.
Departure Bergen - Flåm Sunday, 20.08.2017
Departure At 12:56
Arrivalat 16:55
3h 59min

Thanks Edgar, I appreciate your time and effort. I was hoping to take the train before the 12:56 to Flam but there aren't any tickets left. I noticed there wasn't an option for low price tickets on the 12 56 so it may be close to full too. I bought one to be safe.