Something must have gone wrong with the file ‘LibreOffice_6.2.7_Linux_x86_deb_sdk.tar.gz’ as it was uploaded, because the tar command cannot make sense of it:
$ tar -tf LibreOffice_6.2.7_Linux_x86_deb_sdk.tar.gz
LibreOffice_6.2.7.1_Linux_x86_deb_sdk/
LibreOffice_6.2.7.1_Linux_x86_deb_sdk/DEBS/
LibreOffice_6.2.7.1_Linux_x86_deb_sdk/DEBS/libobasis6.2-sdk_6.2.7.1-1_i386.deb
gzip: stdin: unexpected end of file
tar: Unexpected EOF in archive
tar: Error is not recoverable: exiting now
Also, the signature on the file is bad:
$ gpg --verify LibreOffice_6.2.7_Linux_x86_deb_sdk.tar.gz.asc
gpg: assuming signed data in 'LibreOffice_6.2.7_Linux_x86_deb_sdk.tar.gz'
gpg: Signature made Fri 30 Aug 2019 18:15:25 CEST
gpg: using RSA key C2839ECAD9408FBE9531C3E9F434A1EFAFEEAEA3
gpg: BAD signature from "LibreOffice Build Team (CODE SIGNING KEY) <build@documentfoundation.org>" [unknown]
All other files that I verified (x86 as well as x86-64) are OK.