How to get LMDE6 to offer "install alongside Windows"?

[Aino+]

Is it possible to get the installer to offer me the option to install LMDE6 alongside Windows?

I must be doing something wrong because whatever I try the installer does not give me that option.

I created a bootable USB stick by downloading the latest 64-bit ISO image and in terminal dd copy to usb.

I installed W10 first, and turned off fast boot in the windows power options. And then booted from the LMDE6 installer USB.
Booted both UEFI and non UEFI but it does not give me the option to install alongside Windows. I can only either erase the disk or manually partition the disk.

However, when I boot the Linux Mint 20.2 Cinnamon 64-bit edition live/installer (non UEFI) from a USB stick I made earlier it does give me the option to install alongside Windows.

I tried installing W10 UEFI and non UEFI and tried shrinking the disk first with disk management in windows, but it does not make any difference it will not offer me the option to install alongside Windows.

[MiZoG]

Hey Aino+. Welcome to Mint forums
That "install alongside Windows" option is an Ubuntu ubiquity nicety. LMDE6's installer is calamares-based (I bet it is but I don't bet my shoes on that) Perhaps Mint devs didn't have the time or haven't deemed it a priority to port / replicate this option in LMDE's installer.

Install both OSes in UEFI. First install Windows in UEFI mode. Then just create a single partition out of your freed from Windows storage space formatted as ext4 and mounted at /. Installer will create a 2-gig swapfile and autodetect the UEFI partition created by Windows. Manual partitioning is not as convenient but not really extremely hard. Yet I have to admit that LMDE installer is not the apex of user-friendliness.

[linux-rox]

@Aino+, don't get hung up on the install alongside option. The manual method in LMDE is pretty easy to follow, easier than Ubuntu's (used by Mint's regular edition). Personally, I like to set up partitions before opening the installer, but that's optional.

@MiZoG, I also inferred the LMDE installer is based on Calamares, but turns out it's a separate project.

[Aino+]

Thank you for your replies!

I guess I have no choice but to install it manually... But I am hung up on (really much prefer) the install alongside windows option!
I'll prolly go for Linux Mint Cinnamon instead