The Wittgenstein Project is a multilingual website whose aim is to make available as many of Ludwig Wittgenstein's works as possible, free of charge and with a free license.
Copyright
On 1 January 2021, all of Wittgenstein's work will enter the public domain in countries where rights expire 70 years after the death of the author: this includes most of the European Union, Asia and Oceania, most of Latin American Countries and Canada. (The Wittgenstein Project is based in Italy.)
In other Countries, including but not limited to the United States of America, the authour of a work having died more than 70 years ago is not a sufficient conditiond for determining its copyright status. It's your responsibility to make sure that a given work is in the public domain in your country before accessing it or downloading it.
Resources
The following map may help you to determine the copyright status of a work in your country, although in many cases it is not sufficient alone.
The Wikimedia Commons page on copyright rules by territory provides a more thorough guide to the subject.
If you are based in the United States, the specific Commons page and the Hirlte Chart may be useful to you.