It looks as though your problem is with the fields package rather than Splatter. From a quick look it seems like fields is designed for spatial data. It is not required by Splatter so you should be able to say no to updating fields without any bad effects (unless you are using it for something else).
Splatter is now available in the Bioconductor release so you can run
When I use R 3.3.2 and Bioconductor 3.4, it appears splatter is not available for those versions.
After installing the latest R (3.4.0, and using Bioconductor 3.5 (BiocInstaller 1.26.0), installation completed.
Should I be concerned about any of the following warnings that I got after "library(splatter)"?
Warning: namespace ‘SummarizedExperiment’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘SummarizedExperiment’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘SummarizedExperiment’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘DelayedArray’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘GenomicRanges’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘GenomeInfoDb’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘XVector’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘SummarizedExperiment’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘DelayedArray’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘GenomicRanges’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘GenomeInfoDb’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘XVector’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Warning: namespace ‘SummarizedExperiment’ is not available and has been replaced
by .GlobalEnv when processing object ‘’
Yes you will need those versions of R/Bioconductor, I should have mentioned that in my answer. From a quick google I think those warnings are caused by objects in your workspace. I don't think they should effect your ability to use Splatter.