The large file is located in this Dropbox:  

https://www.dropbox.com/sh/xiir44auwb0mopy/AABBeffw7NSyCgYqoMXqI8zua?dl=0

The large image file is named:
RMB_Painting_verso_high-P_high-M_VIS-mosaic.tif

There is another smaller TIFF in the folder that was also exported from Agisoft Photoscan Pro.  I have no trouble opening a smaller TIFF (28 Mb), only the larger one.  

The smaller file is named:  RMB-Painting_verso_R01C06-0.tif