Lodging will be available in the youth hostel up the hill from the event site as well as local hotels and B&Bs for guests.

The Youth Hostel
Rheinhessische Schullandheim
Burgweg 58, 63897 Miltenberg
Youth hostel website link (In German only)

The Rheinhessische Schullandheim youth hostel is a neogothic building that perches atop the city's highest hill, nearly directly behind (and above) the Alte Rathaus. It takes 5 to 10 minutes to walk from the Rathaus to the hostel. Part of the way is along a long set of outdoor stairs. Photos

Local Hotels and Guest Houses
Miltenberg is a well known tourist location so there are many small hotels and Bed and Breakfast offerings, many within a 10-15 minute walk to the main event site. Breakfast is often included in many hotel and BnB bookings. While some smaller hotels will accept credit cards, it's a good thing to check in advance when making a booking.

A full list of all hotels and guest houses including B&B's can be found here: http://www.miltenberg.info/5_uebern/verzeichnis_miltenberg.pdf The PDF file is in German, so here are some translations of key information:

ab - from
Anzahl - Rooms
Art - Type
Campingplatz - Campground
EZ - Single room
DZ - Double room
Ferienhäuser - Vacation houses
FH - Vacation house (Entire house)
Ferienwohnungen - Guest Houses
FW - Guest house
HP - Breakfast cost
Mobil - Mobile phone
Pers - # guests/people
Preis/Übern. - Price per night
Räume - Rooms
qm - Square meters
ÜF/Pers. - Price per person per night
VP - Full board cost
Wohnmobilstellplatz - Mobile home park

Please note if calling a hotel or guest house from outside Germany, you will need to put the German country code before the telephone number and not dial the first 0. The country code for Germany is 0049.
Example: 09571-80053 is dialed 0049 9571 80053