Can't open level 4 files

[JeromeMathieuEcology]

Hi,

I don't succeed opening the level4 data (either shp or geojson), on Qgis 3.8 and R.

In R I tried:

rgdal::readOGR(dsn = "level4.geojson", layer = "level4")
Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = use_iconv,  : 
  Cannot open data source

rgdal: version: 1.2-12, (SVN revision 681)
 Geospatial Data Abstraction Library extensions to R successfully loaded
 Loaded GDAL runtime: GDAL 2.2.0, released 2017/04/28

I also have an issue with the .mdb file, which seems to be in a old version of the format.

Is there any trick?

Thanks
Jerome