ALI data typically is in GeoTIFF format so the files should open as generic Geotiff. You can use an 'unknown multispectral' as the sensor type in FLAASH. You will need to know the height of the sensor above ground and will need a filter function for this sensor. You will find this help article useful for that: http://www.exelisvis.com/.../ArticleId/4573.aspx You will also need to calibrate the ALI data to radiance prior to input to FLAASH. You can have a look at this code library entry: http://www.exelisvis.com/...x?tabid=1540&id=1316

The two links you mentioned can't be opened, what should I do

This is an old thread with links from 2012. OLI data is natively supported in ENVI now.
https://www.l3harrisgeospatial.com/docs/supportedformats.html